HARDU'ICKE'S SCIENCE-GOSSIP. 



161 



sense speculative, speculation being reserved till the 

 last few pages. Nevertheless, their variance from 

 commonly received ideas makes one hesitate to 

 accept them at once as truth. 



A new kind of warlike apparatus has been proposed 

 and was recently the subject of a lecture by Mr. F. 

 A. Gower. The term "air torpedoes" has been 

 used in reference to it, but Mr. Gower prefers "air 

 battery." Directed balloons, or "aerostats," filled 

 with hydrogen from reservoirs of the compressed gas 

 would be sent to attack forces miles away and by 

 exploding shells of gun-cotton over armies, forts, and 

 arsenals, would expose them to danger in a new 

 way. How they are to be directed from so great a 

 distance did not appear in the report. The lecturer 

 proposed thus " to make the loss of an army a result 

 of its meeting with an opposing wind " ! It is due 

 to his humanity to add that he considers that, on the 

 simplest principles of self-preservation, nations must 

 keep peace, and great armies be disbanded, a propo- 

 sition however, which admits of an opposite opinion. 

 But there is little likelihood of the idea being carried 

 into practice at present. 



In the annual Report of the Public Gardens and 

 Plantations of Jamaica for 1883-4 may be found a 

 good many items of interest. It may surprise those 

 who have paid no attention to the subject to know 

 that a descriptive list is given of over forty varieties 

 of the sugar-cane, introduced into the island in 1882, 

 and that this is by no means all it possesses. Jamaica 

 is said to contain about 500 species of ferns, or one- 

 sixth of the ferns of the whole world. A great loss 

 has been sustained in the cocoa-nut trees by the 

 ravages of rats. The rat which causes this damage is 

 the black species, a good climber, smaller than the 

 brown rat of the cane-fields, and building its nest in 

 the trees A method of defending the cocoa-nut 

 trees which has been found satisfactory, is to nail 

 thin sheets of galvanised iron over the trunk, as the 

 rats cannot pass over this. Various fibre plants are 

 discussed. Bananas form the subject of the chief 

 fruit industry, and the mention of these is followed 

 by that of many other things, oranges, vanilla pods, 

 generally said to be the only economic orchid pro- 

 duct, and olives, of which a consignment of two 

 hundred plants has been received from Italy and 

 distributed with a view to establishing this plant in 

 the island. 



Mr. Galton's method "of composite portraiture 

 has been applied by Professor Pumpelly to obtain type 

 portraits of American scientific men, and the results 

 may be seen in a plate issued by " Science," showing 

 the composite portraits of twelve mathematicians, of 

 sixteen naturalists, of thirty-one academicians, and 

 of twenty-six field-geologists, topographers, &c. The 

 individuals photographed were all taken in the same 

 position, and the camera was so adjusted that the ' 



eyes of each sitter were made to coincide with points 

 marked on the ground glass of the camera. The 

 negatives were then photographed successively with 

 an exposure, in the case of the thirty-one, of two 

 seconds each, and a picture thus produced in which 

 the individualities should be almost imperceptible 

 and only the features more common to all brought 

 out. The results show a singular similarity in all the 

 first three groups. "Science" says that one face 

 will be recognised by most of those who review the 

 faces of American men of science as dominating 

 portraits numbers two and three, while Professor 

 Pumpelly says in his accompanying article that the 

 positives of the mathematicians and of the naturalists 

 suggested, independently to himself and many others, 

 the face of an academician who belongs to a family 

 of mathematicians, and that of a deceased eminent 

 naturalist respectively, neither of whose likenesses 

 are included. It does not seem evident why the eyes 

 should be taken as the points for adjustment. No 

 doubt if they were not, a very confused effect might 

 be produced in that part of the face, but on the other 

 hand the distance between the eyes is variable in 

 different faces, the difference being sometimes con- 

 siderable ; and to make the distance always the same 

 must surely be to improve the eyes at the expense of 

 the other features in the composite portrait. 



The April meeting of the Liverpool and District 

 Association of Science and Art Teachers was devoted 

 to microscopy. A short paper on " The Microscope 

 as an aid in Science Teaching," was read by the 

 president, Mr. Norman Tate, F.I.C., followed by a 

 short discussion, after which some time was devoted 

 to the practical examination of microscopes, apparatus 

 and specimens. 



Inoculation for cholera appears to have taken 

 decided root in Spain, and details given by Dr. 

 Ferran, through Mr. Charles Cameron, M.P., seem 

 to show that it may be a means of warding off the 

 fatal effects of the disease. A test experiment has 

 been conducted by Dr. Ferran at Alcira, a town of 

 about 16,000 inhabitants, near Valencia. During 

 the first three weeks of May, 5432 persons had been 

 inoculated. Of the 10,000 and odd persons not 

 inoculated, cholera had attacked sixty-four and 

 been fatal to thirty. Of the 5,432 inoculated, it had, 

 according to Dr. Ferran, attacked seven and not been 

 fatal in any case ; or, put otherwise, of the uninocu- 

 lated, one in every 163 was attacked and one in 

 every 352 died, while of the inoculated one in every 

 776 was attacked and none died. The circumstances 

 are open to comment, inasmuch as the facts were 

 published by the 20th of May, but it may be pre- 

 sumed that the data were fairly given. The Spanish 

 Government has, however, prohibited Dr. Ferran 

 from inoculating for cholera, pending the result of 

 the inquiries of a commission on the subject. 



